One of the difficult and challenging problems for cigarette makers in recent years has been trying to produce acceptable low-delivery cigarettes that afford adequate flavor of the filtered and diluted smoke. The intrinsic flavor characteristics of tobacco smoke seem to depend to a large extent on the total particulate matter (TPM) contained therein. If most of the TPM is removed by filtration and/or dilution, the remaining smoke has an inadequate or even unacceptable taste. As a result, much of the commercial development effort has been concentrated in the area of blend selection; i.e., combining various types or grades of tobacco in a carefully selected blend effective to achieve somewhat lower delivery of TPM while retaining desired flavor characteristics of the smoke as far as possible and using additions of extrinsic flavorants of various kinds to supplement the natural flavor attributes of tobacco smoke.
The reaction of sugars and amino acids to produce desirable flavorants for smoking materials has generated increased interest. For example, U.S. Pat. No. 3,478,015 describes "browning reactions" in which an amino acid and a sugar having an active carbonyl are reacted in a lower alkyl polyhydric alcohol solvent in the absence of water at a temperature less than 90.degree. C. for about 5 to 15 hours. The resultant reaction mixture is applied in an amount of about 1% by weight to tobacco.
Additional patents or publications that describe the formation of tobacco flavorants from browning-type reactions include, for example, U.S. Pat. No. 3,920,026 and Japanese Pat. Nos. 9239/71 and 3398/73. A review of browning reactions that may occur during tobacco curing, processing and smoking and their importance to tobacco flavoring, published in Recent Advances in Tobacco Science, Volume 2, pages 1-31, 1976, describes the numerous products of browning reactions of amino acids (or ammonia) and sugars present in tobacco and/or smoke.
The reaction products of the present invention differ from conventional browning reactions in that the substitution of carboxylic acids for amino acids results in novel reaction products. They may be described as potentiators that impart organoleptically the qualities that give the sensation of increased strength and fullness to the smoke of tobacco products including reconstituted tobacco, and low delivery smoking products.
Chemical Abstracts 89:126336v describes flavor formulations for tobacco wherein a mixture of ammonia or amino acids, C.sub.1-10 fatty amines, C.sub.2-8 fatty dicarbonyl compounds and/or sugars and nicotine is heated at about 130.degree. for 5 hours to yield tobacco flavorants. Propylene glycol and/or glycerol are used as solvents. Chemical Abstracts 89:126337w describes similar formulations wherein amino acids, C.sub.2-8 fatty dicarbonyl compounds and/or sugars with nicotine are heated to about 150.degree. for 2 hours to produce tobacco flavorants. Water was used as the solvent medium.
U.S. Pat. No. 3,729,009 describes the addition to tobacco of carbamide and saturated fatty acids wherein the fatty acids have a carbon chain length of 16 to 18. The addition, particularly to tobacco blends high in stem material, apparently imparts a more pleasant taste and smell. "Pure" palmitic or stearic acid or mixtures thereof are added to tobacco blends at about 1.0 to 4% by weight of the blend.
U.S. Pat. No. 3,760,815 describes the addition of saturated or unsaturated fatty acids having 6 to 18 carbon atoms in combination with ammonium hydroxide to tobacco for the purpose of releasing pectins contained therein. Generally the fatty acid and ammonia are added to a tobacco slurry, which is maintained at a temperature of about 25.degree. to 110.degree. C. for about 0.5 to 24 hours. After the release of pectins is complete, the slurry is cast to form a sheet of tobacco material. Apparently the longer chain fatty acids, such as, for example, stearic, oleic, linoleic, and linolenic acid, or their ammonium salts, provide a subtle flavor characteristic to the smoke of tobacco treated in this manner.
D. L. Davis in Recent Advances in Tobacco Science, Volume 2, pages 80-111, 1976 describes the importance of waxes and lipids in tobacco leaf and their relationship to smoking quality and aroma. He states, "An important class of lipids, the fatty acids, do contribute to the smoke flavor and aroma. Many of the higher molecular weight fatty acids add a waxy smoothing taste to the smoke; however, linoleic and linolenic add harshness."
We have found, quite surprisingly, that flavor reactions using oleic, linoleic or linolenic acid, as well as other representative fatty acids, in combination with reducing sugars and ammonia provide increased body and strength to the smoke, and particularly the smoke of low delivery cigarettes, without the accompanying harshness as noted by Davis hereinabove.